1. Field of the Invention
The present invention relates to a knit slide fastener having a row of continuous coupling elements knit into and along one longitudinal edge portion of a knit fastener tape as the fastener tape is knit.
2. Description of the Prior Art
A conventional knit slide fastener disclosed, for example, in Japanese Patent Publication No. 38-11673 includes a fastener tape knit with chain stitches and laid-in weft threads and having a longitudinal edge portion into and along which a row of continuous coupling elements formed from a nylon monofilament is knit. The nylon monofilament is laid transversely across the longitudinal tape edge portion and shaped into the row of coupling elements knit successively in the chain stitches as the fastener tape is knit. Another known knit slide fastener disclosed in U.S. Pat. No. 5,035,125 includes a fastener tape knit with chain stitches and a laid-in weft thread, and a row of continuous coupling elements formed from a plastic monofilament laid in and along one longitudinal edge portion of the fastener tape. In the longitudinal tape edge portion, the laid-in weft thread is interlaced with the chain stitches running along two adjacent wales to downwardly urge the upper legs of the coupling elements, and also with the chain stitches running along a neighboring wale to downwardly urge the lower legs of the coupling elements.
The conventional knit slide fasteners previously described are of the type including a fastener tape knit with chain stitches and laid-in weft threads, and a plastic monofilament laid into one longitudinal edge portion of the fastener tape so as to form a row of continuous coupling elements knit into and along the longitudinal tape edge portion. In the first-mentioned knit slide fastener, the row of coupling elements is secured by sinker loops of the chain stitches provided to form a ground structure of the fastener tape. Since the chain stitches are longitudinally stretchable, the row of coupling elements thus attached is dimensionally instable and is likely to be deformed when the chain stitches are stretched. The row of coupling elements thus deformed is no longer able to insure a smooth interlocking engagement with a mating row of coupling elements. In the second-mentioned knit slide fastener, needle loops of the chain stitches are merely interlaced with the laid-in weft thread extending transversely across the longitudinal tape edge portion, and the chain stitches urging the legs of the coupling elements downwardly also consists a portion of the ground structure. The chain stiches thus arranged are also readily stretchable in the longitudinal direction and hence cannot secure the coupling elements with sufficient dimensional stability. A smooth interlocking engagement between the opposed rows of coupling elements is, therefore, difficult to achieve.